code: def _get_phis(window_size, length):
      phis = np.zeros(length)
      i = np.arange(length // 2)
      const = 2 * np.pi / window_size
      phis[0::2] = np.cos((-i) * const)
      phis[1::2] = -np.sin((-i) * const)
      return phis
  
file_path: sktime/sktime/transformations/panel/dictionary_based/_sfa_fast_numba.py
imports: import math
  from warnings import simplefilter
  import numpy
  from sktime.utils.numba.njit import njit
  from sktime.utils.validation._dependencies import _check_soft_dependencies
label_desc: Use image node_id 6 for calling a global function with example usage: _get_phis(window_size, length) and returns: phis